Downhole bypass valve

ABSTRACT

A downhole bypass valve in which a tubular mandrel is slidable between an upper position and a lower position in a tubular member at the lower end of a drill string. A lateral opening in the tubular mandrel uncovers a port in the tubular member to allow flow between the central bore of the tubular member and the annulus surrounding the drill string. A valve in the bore of the tubular mandrel closes as the tubular mandrel moves to the upper position and opens as the mandrel moves to the lower position. Movement of the mandrel relative to the tubular member is prevented by a ring extending from the outer surface of the tubular mandrel into a liquid-filled chamber in the tubular member until the spring biasing of check valves is overcome to allow flow through passages through the ring.

United States Patent Mori Aug. 26, 1975 [54] DOWNHOLE BYPASS VALVE 3,371,729 3/1968 Carr 175/317 X 3,461,962 8/1969 Harrington... 175/321 X [75] invent Ernest Pmsburgh, 3,667,557 6/1972 Todd et a1. 175/318 x 73 Assigneez Gulf Research & Development 3,799,278 3/1974 Oliver 175/237 Company, Pittsburgh, Pa.

Primary Examiner-David H. Brown [22] Filed: Oct. 29, 1974 211 App]. N0.: 518,299

24 1 l i /32 32a- 7 57 ABSTRACT A downhole bypass valve in which a tubular mandrel is slidable between an upper position and a lower position in a tubular member at the lower end of a drill string. A lateral opening in the tubular mandrel uncovers a port in the tubular member to allow flow be tween the central bore of the tubular member and the annulus surrounding the drill string. A valve in the bore of the tubular mandrel closes as the tubular mandrel moves to the upper position and opens as the mandrel moves to the lower position. Movement of the mandrel relative to the tubular member is prevented by a ring extending from the outer surface of the tubular mandrel into a liquid-filled chamber in the tubular member until the spring biasing of check valves is overcome to allow flow through passages through the ring. 1

10 Claims, 9 Drawing Figures DOWNHOLE BYPASS VALVE This invention relates to the rotary drilling of wells and more particularly to a bypass valve that will allow circulation of liquids from a drill string to the annulus surrounding the drill string without passing through nozzles in the drill bit.

In the rotary drilling process, a drill bit connected to the lower end of a drill string rotates at the bottom of the borehole of the well to break particles from the bottom. A fluid, ordinarily referred to as a drilling mud, is circulated down through the drill string and out through nozzles in the drill bit to wash rock cuttings from the bottom of the borehole and carry them up through the annulus surrounding the drill string to the surface. Cuttings are separated from the drilling mud and the drilling mud is recirculated through the well for further drilling. One rotary drilling process that has recently been developed is the abrasive jet drilling process in which small particles of abrasive are suspended in the drilling mud and discharged at a very high velocity from nozzles in the drill bit to erode rock from the bottom of the borehole. The nozzles in drill bits for abrasive jet drilling have a small diameter which allows the drilling mud to be discharged from the nozzles at an extremely high velocity without excessive drilling mud circulation rates.

On some occasions during the drilling of a well, loss of circulation of the drilling mud is encountered as a result of drilling mud flowing into formations penetrated by the well. The loss of circulation may be caused by the penetration of formations having an extremely high permeability, but usually lost circulation is the result of fracturing of formations penetrated by the well as a result of excessive pressures developed by the drilling mud. One method of counteracting loss of circulation is to add a lost circulation material, such as fibrous or granular solid particles, which bridges over openings in the formations causing loss of circulation and provides a seal which reduces the rate of flow of drilling mud into such formations. The size of the particles ordinarily used as a lost circulation material can plug nozzles in the drill bit, and for that reason it is desirable to have a means of bypassing the drill bit during the circulation of the lost circulation material.

From time to time during the drilling of a well, it is necessary to replace the drill bit. Replacement of the drill bit requires pulling the drill string from the well, replacing the drill bit, and then lowering the drill string with the new bit into the well. It is desirable that drilling mud in the drill string drain freely from the lower end of the drill string as the drill string is being pulled to prevent spilling of drilling mud onto the floor of the platform at the wellhead. Sometimes it is desirable to fill the drill string as it is run into the hole by flowing drilling mud from the hole into the lower end of the drill string as the drill string is run into the hole. Because the drilling mud in the'hole contains cuttings, it is desirable to isolate drilling mud entering the drill string from the drill bit to avoid plugging of nozzles in the drill bit.

A number of different structures have been suggested for bypassing the flow of drilling mud around drill bits. Such structures are disclosed in the following patents:

US. Patent No. Patentees Issued 2,307,658 Appleby 1-43 3,369.6") Brown 2-68 3,667,557 Todd et al 6-72 3,768,556 Baker 10-73 This invention resides in a downhole bypass valve in which a tubular mandrel is longitudinally slidable in a tubular member that forms a part of the drill string. The mandrel or a tubular sub connected to its lower end extends from the lower end of the tubular member for connection directly to the drill bit. A cam-operated cutoff valve mounted in the mandrel closes the bore of the mandrel when the mandrel is in an upper position and opens the bore for flow through the drill bit when the mandrel is at a lower position. At the upper position of the mandrel, a lateral opening therein uncovers a port in the tubular member to provide a bypass around the drill bit. A ring around the mandrel extends into a chamber formed by a recess in the inner wall of the tubular member and acts as a piston opposing movement of the mandrel relative to the tubular member until the force applied to the mandrel overcomes springs that urge check valves in passages through the ring toward a closed position.

In the drawings:

FIG. 1 is a diagrammatic view in elevation of a drill string extending down a well with a drill bit at the lower end of the drill string suspended off bottom.

FIG. 2a is an elevational view, partially in vertical section, of the upper end of the bypass valve of this invention showing the valve in the open position.

FIG. 2b is an elevational view also partially in vertical section of the lower portion of the bypass valve of this invention in the open position.

FIG. 3a is an elevational view partially in vertical section of the bypass valve of this invention with the valve element in the closed position and a control valve open to permit flow to the drill bit.

FIG. 3b is an elevational view also partially in vertical section of the lower end of the bypass valve in the closed position.

FIG. 4 is a horizontal sectional view taken along section line IV-IV in FIG. 2b illustrating a spline arrangement for prevention of rotation of the mandrel relative to the tubular member.

FIG. 5 is a horizontal sectional view along section line VV in FIG. 3a showing the mounting of the control valve.

FIG. 6 is a view along section line VIVI in FIG. 2a of the cam that actuates the bypass valve when the bypass valve is in the open position.

FIG. 7 is a view along section line VII-VII in FIG. 3a of the cam and cam follower when the valve is in the closed position.

Referring to FIG. 1 of the drawings, a well indicated generally by reference numeral 10 is shown with casing 12 extending part of the way down the borehole of the well and with open hole indicated by reference numeral 14 at the lower end of the borehole. Extending-down the well is a drill string 16 having a kelly 18 at its upper end extending through a rotary table 20. The bypass valve of this invention indicated generally by reference numeral 22 has a drill bit 23 connected to its lower end.

Referring to FIGS. 2a and 2b, the bypass valve 22 includes a tubular member 24 consisting of an upper section 24a, a middle section 24b and a lower section 24c connected together by threads and provided with suitable seals to prevent leakage at the connections. Tubular member 24a is connected at its upper end to the drill string 16 by threads 26 whereby rotation of the drill string causes rotation of the tubular member. A plurality of ports 28 extending laterally through tubular member section 24a are enlarged at their outer end to receive a plug 30 which can be forced outwardly into the annulus, but not inwardly.

Longitudinally slidable in tubular member 24 is a tubular mandrel 32 consisting of an upper section 32a, a middle section 32b and a lower section 32c. Lateral openings 34 through the upper section 32a of the tubular mandrel are positioned to uncover ports 28 when the tubular mandrel is in its uppermost position relative to the tubular member 22. The openings 32 and ports constitute a bypass valve allowing flow from the bore to the annulus when the tubular member is in the upper position. Upper section 32a and middle section 32b are connected together by threads.

A cut-off valve designated by reference numeral 35 comprises a disc 36 mounted on a shaft 38 adapted to rotate in the upper section 32a from a closed position with disc 36 extending transverse of the bore of the tubular member, as illustrated in FIG. 2a, to an open position, illustrated in FIG. 3a, in alignment with the bore of the mandrel. The position of the disc 36 is governed by engagement of a cam follower 40 secured to the end of shaft 38 with a cam 42 in a cavity 43 in the inner wall of upper section 24a of the tubular member 24. As shown in FIGS. 6 and 7 of the drawings, the disc extends horizontally across the bore of the mandrel when the mandrel is in the upper position and in vertical alignment with the bore when the mandrel is in the lower position. Cut-off valve 35 may be a rotating plug or rotating ball type instead of the butterfly type valve illustrated in the drawings.

The upper end of lower section 24c of the tubular member has an internal diameter larger than the exter nal diameter of middle section 32b of the mandrel to form a chamber 44 surrounding middle section 32b of the mandrel 32. A ring 46 that protrudes from the outer surface of section 32b into chamber 44 acts as a piston in the chamber. Leakage between the outer surface of ring 46 and the inner wall of section 24c is prevented by suitable sealing means 48. Chamber 44 contains a liquid introduced through an opening 58 closed by a suitable plug 60.

A plurality of vertical passages 50 extend through the ring 46. Each of passages 50 contains a check valve 51 consisting of a ball 52 urged toward a closed position against a valve seat 54 by a helical spring 56. Some of the check valves 51 allow flow upwardly through the passages in the ring 44 when the force exerted by the spring 56 is exceeded. Other of the check valves 51 allow flow downwardly through passages 50 when the force exerted by the helical spring 56 is exceeded.

The internal surface at the lower end of section 240 of the tubular element 24 is nonround and enlarged to provide a cavity 62 surrounding the lower section 32c of the tubular mandrel. Lower section 32c of the tubular mandrel is milled, as indicated at 64, to provide a plurality of shoulders 66 adapted to receive a spline 68. Spline 68 consists of two parts, each covering 180, to

facilitate assembly of the spline in the groove on the outer surface of middle section 32b. In the embodiment of the invention illustrated in the drawings, the nonround section is octagonal in shape and milling of the section 32c provides eight shoulders 66. Spline 68 rests on the shoulders and is held in place on the shoulders by engagement with the inner wall 70 of section 240 of the tubular member. The lower end of cavity 62 is closed by the upper end of a cap 24d which screws into the lower end of section 24c. Cap 24d is essentially an extension of tubular member 24 and is separate from section 24c only to facilitate manufacture, particularly cutting of the nonround opening in the lower end of section 24c. Lower section 32c of the tubular mandrel extends downwardly below cap 24d and is connected either directly or indirectly through a suitable sub with drill bit 23. The extent of movement of the tubular mandrel 32 is limited by engagement of the spline 68 with the ends of chamber 44.

The tubular mandrel 32 can be either in the upper position illustrated in FIG. 2a or the lower position illustrated in FIG. 3a as the tubing string is run into the well. If the tubular mandrel is in the upper position with disc 36 in the horizontal position as the bit is run into the hole, the plugs 30 in the ports 28 prevent flow from the annulus through ports 28 into the drill string. If desired, the drill string can be filled from the top as it is run into the hole with the tubular member in the upper position. If it is desired to fill the drill string from the bottom as the drill string is run into the hole and without upward flow through the drill, plugs 30 can be removed before the bypass valve is lowered into the hole.

When the drill string reaches bottom and it is desired to circulate liquid through the well before commencing drilling, liquid is pumped down the drill string at a rate that will increase the pressure within the tubular mandrel sufficiently to blow the plugs 30 from the ports 28. Liquid is then circulated down the drill string and through lateral openings 34 in the tubular mandrel and the ports 28 in the tubular member into the annulus to remove debris from the hole before drilling is commenced. Downward movement of the tubular mandrel relative to the tubular member while circulating is prevented by the valves in ring 46. It is contemplated that the openings 34 and ports 28 will allow a circulation rate approximately to percent of the maximum circulation rate used during drilling before the downward force on the tubular mandrel is adequate to overcome the force exerted by springs 56 and open the valves 51 closing passage 50 in ring 46.

When it is desired to commence drilling, the drill string is lifted to raise the drill bit ofibottom and the rate of circulation of liquid is increased to develop a pressure above disc 36 adequate to create a force that overcomes the springs 56 and forces check valves 51 to open and allow upward flow of liquid through passages 50. The tubular mandrel then moves downwardly relative to the tubular member until spline 68 engages the lower end of chamber 70. At that position, the openings 34 are no longer in alignment with ports 28; consequently, all of the liquid pumped down the drill string is directed through the drill bit. When the tubular mandrel is in the lower position, disc 36 is in alignment with the bore of the tubular mandrel and offers minimum resistance to flow of drilling mud or other liquid to the drill bit. The drill string is rotated and the drill bit lowered against the bottom of the hole. The spline 68 engages the nonround surfaces of the tubular member 24 and the nonround surfaces of the lower section of the tubular mandrel to transmit rotation of the drill string to the tubular mandrel and therefore to the drill bit. The excess of pressure within the drill bit over the pressure in the borehole outside of the drill bit exerts a downward force on the tubular member adequate to maintain the tubular mandrel in the lower position relative to the tubular member during drilling.

When it is desired to pull the drill bit from the well, pumping of liquid down the drill string is stopped. The drill string is lowered to place enough weight on the bit to overcome the helical springs in those check valves 52 that allow downward flow through the passages 50. The tubular member moves downwardly relative to the mandrel to locate the mandrel at the upper position at which the lateral opening 34 is in alignment with ports 28. As the drill string is pulled from the hole, liquid in the drill string drains through ports 28 to permit a dry string to be pulled.

The provision of the spring-loaded check valves controlling flow through the passages 50 is effective in preventing accidental movement of the tubular mandrel from the desired upper or lower position. A positive force which can be as large as desired by suitable design of the check valves is required before a hydraulic liquid in the chamber 44 can flow through the passages. Additionally, the passages act as an orifice limiting the rate of flow of hydraulic fluid from above to below the ring 51, or vice versa, to minimize shock as the tubular mandrel is moved from either the upper or lower position to the other position. The rotation of disc 36 about a central axis further contributes to reduction of shock by allowing flow to the drill bit to increase gradually as valve 35 is opened.

I claim:

1. A downhole bypass valve for positioning in a drill string above the drill bit comprising a tubular member adapted to be connected in and to form a part of the drill string, said tubular member having a longitudinal opening therethrough, a port extending laterally through the tubular member, a mandrel slidable in the tubular member between an upper position and a lower position, said mandrel having a longitudinal opening therethrough and extending below the lower end of the tubular member for suspension of the drill bit, a lateral opening through the mandrel positioned for uncovering the port when the mandrel is in the upper position and covering the port when the mandrel is in the lower position, a cut-off valve mounted in the mandrel below the lateral opening for movement from a closed position closing the longitudinal opening through the mandrel to an open position, cam means adapted to operate the cut-off valve to open the cut-off valve when the mandrel is at the lower position and close the cut-off valve when the mandrel is at the upper position, and means preventing rotation of the tubular mandrel relative to the tubular member.

2. A bypass valve as set forth in claim 1 in which the port in the tubular member is larger adjacent the outer surface of the tubular member than at the inner surface and a plug positioned in the port prevents flow from outside the tubular member into and through the port, said plug being removable from the port by a predetermined excess of the pressure inside of the tubular member over the pressure outside of the tubular member.

3. A bypass valve as set forth in claim 1 in which the cut-off valve is rotatably mounted in the mandrel and the cam means rotate the cut-off valve on movement of the mandrel relative to the tubular member.

4. A bypass valve as set forth in claim 3 characterized by the cut-off valve comprises a shaft rotatably mounted in the mandrel and a disc secured to the shaft, a recess in the inner surface of the tubular member, and the cam means comprise a cam in the recess, and a cam follower on the end of the shaft extending into the recess and engaging the cam to close the cut-off valve when the mandrel is in the upper position and open the cut-off valve when the mandrel is at the lower position.

5. A bypass valve as set forth in claim 1 including means resisting longitudinal movement of the mandrel relative to the tubular member, said means resisting movement permitting longitudinal movement of the mandrel relative to the tubular member on application of a predetermined minimum force.

6. A bypass valve as set forth in claim 5 in which the means resisting movement comprise an annular recess in the inner wall of the tubular member forming a chamber between the tubular member and the mandrel, a ring extending from the outer surface of the mandrel into the chamber, means preventing leakage between the ring and the tubular member, passages extending longitudinally through the ring and check valves spring-biased to a closed position controlling flow through the passages, at least one of the check valves permitting flow downwardly through a passage to permit upward movement of the mandrel relative to the tubular member, and at least one check valve permitting flow upwardly through a passage to permit downward movement of the tubular mandrel relative to the tubular member.

7. A bypass valve as set forth in claim 6 in which the check valves comprise a valve seat, a ball adapted to engage the valve seat to prevent flow through the passage and a compressed spring urging the ball against the valve seat.

8. A bypass valve as set forth in claim 1 in which the means for preventing rotation of the mandrel relative to the tubular member comprise a spline means.

9. A bypass valve as set forth in claim 8 in which the spline means comprise a portion of the inner wall of the member having a nonround shape in horizontal section, a groove in the outer wall of the mandrel, said groove being of nonround shape in horizontal section, and a ring in said groove in the mandrel engaging the groove and extending outwardly therefrom to engage the nonround inner surface of the tubular member to prevent relative rotation of the tubular member and the mandrel.

10. A valve as set forth in claim 9 in which the ring comprises two sections, each section extending over approximately 

1. A downhole bypass valve for positioning in a drill string above the drill bit comprising a tubular member adapted to be connected in and to form a part of the drill string, said tubular member having a longitudinal opening therethrough, a port extending laterally through the tubular member, a mandrel slidable in the tubular member between an upper position and a lower position, said mandrel having a longitudinal opening therethrough and extending below the lower end of the tubular member for suspension of the drill bit, a lateral opening through the mandrel positioned for uncovering the port when the mandrel is in the upper position and covering the port when the mandrel is in the lower position, a cut-off valve mounted in the mandrel below the lateral opening for movement from a closed position closing the longitudinal opening through the mandrel to an open position, cam means adapted to operate the cut-off valve to open the cut-off valve when the mandrel is at the lower position and close the cut-off valve when the mandrel is at the upper position, and means preventing rotation of the tubular mandrel relative to the tubular member.
 2. A bypass valve as set forth in claim 1 in which the port in the tubular member is larger adjacent the outer surface of the tubular member than at the inner surface and a plug positioned in the port prevents flow from outside the tubular member into and through the port, said plug being removable from the port by a predetermined excess of the pressure inside of the tubular member over the pressure outside of the tubular member.
 3. A bypass valve as set forth in claim 1 in which the cut-off valve is rotatably mounted in the mandrel and the cam means rotate the cut-off valve on movement of the mandrel relative to the tubular member.
 4. A bypass valve as set forth in claim 3 characterized by the cut-off valve comprises a shaft rotatably mounted in the mandrel and a disc secured to the shaft, a recess in the inner surface of the tubular member, and the cam means comprise a cam in the recess, and a cam follower on the end of the shaft extending into the recess and engaging the cam to close the cut-off valve when the mandrel is in the upper position and open the cut-off valve when the mandrel is at the lower position.
 5. A bypass valve as set forth in claim 1 including means resisting longitudinal movement of the mandrel relative to the tubular member, said means resisting movement permitting longitudinal movement of the mandrel relative to the tubular member on applicaTion of a predetermined minimum force.
 6. A bypass valve as set forth in claim 5 in which the means resisting movement comprise an annular recess in the inner wall of the tubular member forming a chamber between the tubular member and the mandrel, a ring extending from the outer surface of the mandrel into the chamber, means preventing leakage between the ring and the tubular member, passages extending longitudinally through the ring and check valves spring-biased to a closed position controlling flow through the passages, at least one of the check valves permitting flow downwardly through a passage to permit upward movement of the mandrel relative to the tubular member, and at least one check valve permitting flow upwardly through a passage to permit downward movement of the tubular mandrel relative to the tubular member.
 7. A bypass valve as set forth in claim 6 in which the check valves comprise a valve seat, a ball adapted to engage the valve seat to prevent flow through the passage and a compressed spring urging the ball against the valve seat.
 8. A bypass valve as set forth in claim 1 in which the means for preventing rotation of the mandrel relative to the tubular member comprise a spline means.
 9. A bypass valve as set forth in claim 8 in which the spline means comprise a portion of the inner wall of the member having a nonround shape in horizontal section, a groove in the outer wall of the mandrel, said groove being of nonround shape in horizontal section, and a ring in said groove in the mandrel engaging the groove and extending outwardly therefrom to engage the nonround inner surface of the tubular member to prevent relative rotation of the tubular member and the mandrel.
 10. A valve as set forth in claim 9 in which the ring comprises two sections, each section extending over approximately 180*. 